1. Field of the Invention
This invention relates to a semiconductor memory device and, more particularly, to techniques which are effective when utilized for, e.g., an EPROM (erasable and programmable read only memory) associated with a nonvolatile semiconductor memory device into which information can be electrically written.
2. Description of Related Subject Matter
An example of an EPROM into which information data are simultaneously written, such as, in the form of a plural-byte information data or in the form of a plural-word unit of information data, is disclosed in Japanese Patent Application publication No. 59-152592, laid-open on Aug. 31, 1984.
Owing to the progress of semiconductor integrated circuit technology, the microfabrication of devices has been achieved, and the direction of development continues to be towards enlarging the storage capacity, that is the storage capability of such memory devices even further. With such increases in the storage capacity of such memory devices, remedying defects associated therewith has become indispensable in enhancing the usable capacity or portion of the device or in the available percentages of the products being manufactured for use. Accordingly, redundant (spare) data lines for remedying defects should to be laid-out or provided in the EPROM which is, furthermore, characterized as having the function of simultaneously writing a plurality of bytes or words as stated above, namely, a so-called "page program mode." The aforementioned EPROM, however, adopts a type of construction in which write information data items corresponding to the plurality of bytes or words are held in latch circuits through column switches and write signals are collectively transmitted to data lines for the plurality of bytes or words in accordance with the information data items held. Therefore, when the redundant data lines are laid-out or provided in connection with such an EPROM for the writing of a plural-byte or plural-word information data type unit, there arises the problem that the area of the memory device must inevitably become enlarged. Moreover, when a function such as that of the page program mode, described above, is added, there, furthermore, arises the problem that the number of external terminals required for setting the mode must necessarily be increased.